- Summary of Changes in Accumulated Other Comprehensive Loss for Pension Plan Items (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss beginning balance	$ (8,652)
Other comprehensive income before reclassifications	(27)
Amounts reclassified from accumulated other comprehensive loss	1,162
Total other comprehensive income (loss), net of tax	1,135	1,228	666
Accumulated other comprehensive loss ending balance	(7,517)	(8,652)
Settlement cost	0	2,503	1,106
Investment income, net	1,498	1,219	1,130
Net income	4,966	5,990	(330,308)
Defined Benefit Pension Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss beginning balance	(8,652)
Other comprehensive income before reclassifications	2,191
Amounts reclassified from accumulated other comprehensive loss	1,069
Total other comprehensive income (loss), net of tax	3,260
Accumulated other comprehensive loss ending balance	(5,392)
Defined Benefit Pension Items | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Amortization of loss	326
Settlement cost	743
Net income	1,069
Unrealized Gains and Losses on Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss beginning balance	0
Other comprehensive income before reclassifications	(2,218)
Amounts reclassified from accumulated other comprehensive loss	93
Total other comprehensive income (loss), net of tax	(2,125)
Accumulated other comprehensive loss ending balance	(2,125)
Unrealized Gains and Losses on Available-for-Sale Securities | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net income	$ 1,162